题目

These days we are exposed to ads wherever we go. They try to sell us products by using beautiful art, videos, images or slogans that are catchy. Below, you can find some of the most famous logos that you can see everywhere in your life. Audi This business logo is very popular and the company is a competitor of BMW. The four rings can be interpreted as many things, like four elements, or four nations, but the truth lies elsewhere. In the 1930s, there were four different car manufacturers in Germany and they were called Audi, DKW, Horch and Wanderer. They decided to get together and creat如图所示，质量为m的物体放在水平放置的钢板C上，与钢板的动摩擦因素为μ。由于受到相对于地面静止的光滑导槽A、B的控制，物体只能沿水平导槽运动。现使钢板以速度v1向右匀速运动，同时用力F拉动物体（方向沿导槽方向）使物体以速度v2沿导槽匀速运动。则下列说法中正确的是（　　　　）A．物体受到四个力的作用B．物体受到的摩擦力C．拉力F小于物体受到的摩擦力fD．拉力F大于物体受到的摩擦力f